Geolocator study reveals east African migration route of Central European Common Terns

Background: The majority of European Common Terns(Sterna hirundo) migrate south along the western coast of Europe and Africa, while birds from eastern regions are known to cross the Mediterranean Sea from east to west or migrate along the eastern African coast. The migration route of north European terns wintering along the coast of western Africa was already described using geolocator data, while knowledge about movements of the European inland populations is based only on relatively scarce recoveries of ringed birds.Methods: We used light-level geolocators in inland Common Tern colonies in Hungary and Croatia to study their migration route and to identify wintering areas along with stopover sites. Results revealed by geolocators were compared with recoveries of ringed birds.Results: All tracked birds used the east African migration route with autumn stopovers at Lower Nile and in the southern part of the Red Sea, and short spring stopover in Israel. Terns wintered along Kenyan coasts and in the southern Mozambique Channel. Autumn migration lasted four times longer than spring migration.Conclusions: This is the first geolocator study that describes the east African migration route of the Common Tern. Important stopover sites were identified. More studies of inland populations are needed to better elucidate tern winter movements.

Citrine Wagtail migration on the Indo-European flyway:a first geolocator track reveals alternative migration route and endurance flights to cross ecological barriers

Most long-distance migrating passerines that breed in Europe spend their winters in Africa,with only a few species migrating eastward to spend the non-breeding period in South Asia.The use of the Indo-European flyway is rare and has been poorly studied so far.However,it is extremely interesting as within that system we are currently witnessing a recent range expansion of European breeding long distance migrants and thus the lengthening of migration routes.It may therefore conceal a unique migratory strategies and behaviour that can help us to understand the underlying factors and mechanisms determining the evolution of migration routes,strategies and breeding range extinction.Based on light-level geolocator we reveal a first track of the Citrine Wagtail(Motacilla citreola)migration,providing insight into the migration pattern,timing and behaviour of the species that recently has extended its migration routes.Unexpectedly,the studied individual did not retrace a recent range expansion that runs north and east from the Caspian Sea but followed a migration route running south form the Caspian sea,suggesting possible presence of an alternative species range expansion.The overall migration distance between the breeding site in Poland and the non-breeding site in Pakistan was about 10,420 km and included two endurance movement phases(920 and 2240 km)covering 30%of the whole journey length,with an average movement speed of 574 km/day.We explain this migration behaviour as an adaptation for crossing the ecological barriers imposed by arid environments.

Migration pattern of a population of Barn Swallows(Hirundo rustica)breeding in East Asian tropical region

Birds exhibit a high degree of migratory diversity,which is influenced by various ecological factors and life history strategies.Conducting studies on tropical bird migration,of which research is scarce,and comparing it with temperate birds can enhance our understanding of bird migration behaviour and its underlying mecha-nisms.In this study,we explored the migration behaviour of a breeding population of the Barn Swallow(Hirundo rustica)in Zhanjiang,southern China,a region located in the northern tropics,using light-level geolocators.From 2021 to 2023,we deployed geolocators on 92 breeding swallows and retrieved geolocators successfully from 23 individuals.These swallows all exhibited migratory behaviour,and wintering on various islands in Southeast Asia.They displayed sex differences in their wintering locations.All males concentrated in Borneo,while females primarily chose Borneo but also dispersed to the Philippines,South China Sea,and Vietnam for wintering.The studied swallow population adopted a seasonal migration pattern of“indirect in autumn,direct in spring”,bypassing the ecological barrier of the South China Sea in autumn and tending to directly cross it in spring migration.Moreover,the distance and duration of autumn migration was significantly longer than those of the spring migration.Compared to temperate Barn Swallows,the Barn Swallow population breeding in Zhanjiang adopts a pattern of“intra-tropical migration”and initiates autumn migration earlier.The formation of their migration pattern may be limited by ecological and physiological factors.

A meta-analysis of the effects of geolocator application on birds

An increasing trend in use of tracking devices such as geolocators is based on the assumption that the information gathered from such devices provides reliable information about the migratory behavior of free-living birds. This underlying as- sumption is rarely tested, as evidenced by the absence in many studies of controls, in particular treated controls, and so far never with a reasonable statistical power. Published studies have shown reduced survival prospects or delayed breeding in some species, suggesting that there may be reason to doubt that tracking devices provide unbiased information. Therefore, we conducted a meta-analysis of studies applying geolocators to wild birds to determine whether geolocators affected fitness components. Ge- olocators had an overall negative effect on fitness components, in particular survival, and ecological variables. Effect size was larger for aerial foragers than for other species. Moreover the leg band attachment method was more detrimental for birds than the leg-loop backpack harness. A meta-regression model of effect size showed independent negative effects of geolocators on ae- rial foragers, smaller species, species with smaller migration distances and in studies where geolocators were attached with a ring. These results suggest that geolocator studies should be interpreted with caution, but also raise questions whether it is ethically defensible to use geolocators on aerial foragers or small species without carrying out robust pilot studies.

Integrating Neighborhood Geographic Distribution and Social Structure Influence for Social Media User Geolocation

Geolocating social media users aims to discover the real geographical locations of users from their publicly available data,which can support online location-based applications such as disaster alerts and local content recommen-dations.Social relationship-based methods represent a classical approach for geolocating social media.However,geographically proximate relationships are sparse and challenging to discern within social networks,thereby affecting the accuracy of user geolocation.To address this challenge,we propose user geolocation methods that integrate neighborhood geographical distribution and social structure influence(NGSI)to improve geolocation accuracy.Firstly,we propose a method for evaluating the homophily of locations based on the k-order neighbor-hood geographic distribution(k-NGD)similarity among users.There are notable differences in the distribution of k-NGD similarity between location-proximate and non-location-proximate users.Exploiting this distinction,we filter out non-location-proximate social relationships to enhance location homophily in the social network.To better utilize the location-proximate relationships in social networks,we propose a graph neural network algorithm based on the social structure influence.The algorithm enables us to perform a weighted aggregation of the information of users’multi-hop neighborhood,thereby mitigating the over-smoothing problem of user features and improving user geolocation performance.Experimental results on real social media dataset demonstrate that the neighborhood geographical distribution similarity metric can effectively filter out non-location-proximate social relationships.Moreover,compared with 7 existing social relationship-based user positioning methods,our proposed method can achieve multi-granularity user geolocation and improve the accuracy by 4.84%to 13.28%.

Performance validation of High Mountain Asia 8-meter Digital Elevation Model using ICESat-2 geolocated photons

High Mountain Asia(HMA),recognized as a third pole,needs regular and intense studies as it is susceptible to climate change.An accurate and high-resolution Digital Elevation Model(DEM)for this region enables us to analyze it in a 3D environment and understand its intricate role as the Water Tower of Asia.The science teams of NASA realized an 8-m DEM using satellite stereo imagery for HMA,termed HMA 8-m DEM.In this research,we assessed the vertical accuracy of HMA 8-m DEM using reference elevations from ICESat-2 geolocated photons at three test sites of varied topography and land covers.Inferences were made from statistical quantifiers and elevation profiles.For the world’s highest mountain,Mount Everest,and its surroundings,Root Mean Squared Error(RMSE)and Mean Absolute Error(MAE)resulted in 1.94 m and 1.66 m,respectively;however,a uniform positive bias observed in the elevation profiles indicates the seasonal snow cover change will dent the accurate estimation of the elevation in this sort of test sites.The second test site containing gentle slopes with forest patches has exhibited the Digital Surface Model(DSM)features with RMSE and MAE of 0.58 m and 0.52 m,respectively.The third test site,situated in the Zanda County of the Qinghai-Tibet,is a relatively flat terrain bed,mostly bare earth with sudden river cuts,and has minimal errors with RMSE and MAE of 0.32 m and 0.29 m,respectively,and with a negligible bias.Additionally,in one more test site,the feasibility of detecting the glacial lakes was tested,which resulted in exhibiting a flat surface over the surface of the lakes,indicating the potential of HMA 8-m DEM for deriving the hydrological parameters.The results accrued in this investigation confirm that the HMA 8-m DEM has the best vertical accuracy and should be of high use for analyzing natural hazards and monitoring glacier surfaces.

基于Android的WebGIS地理定位服务研究

利用最新的互联网HTML5 Geolocation定位技术,调用已发布的ArcServer地图服务,并在Android平台的基于位置感知Web应用程序中实现实时跟踪和快速准确地理定位。

基于Android的WebGIS地理定位服务

Android平台上基于位置的服务(LBS)大都是本地应用程序,难以适应WebGIS的新需求,而且传统定位技术需要复杂的脚本来解析设备地理信息数据,以实现移动设备的定位追踪功能,这无疑加重了开发人员的负担。利用最新的互联网HTML5 Geolocation定位技术,调用Arcserver地图服务,并在Android平台的基于位置感知Web应用程序中实现了实时跟踪和快速准确地理定位。

基于Geolocation API的Html5地理位置追踪定位的实现

随着移动网络时代的到来,基于地理位置定位的位置服务类Web应用显得越来越重要,Html5作为新一代的网页设计的技术标准,它提供了Geolocation API接口,能便捷地实现地理位置的定位与跟踪,并允许用户将所得到的位置信息与Google Map及百度地图的开放平台相结合,获取指定位置相关的周边地图信息及商业信息,这一功能可以帮助开发者开发基于位置服务的各种应用程序。

HTML5中的地理定位技术探究

获取定位信息的方式有很多种,精度最高的要数GPS技术,除此之外还可以通过IP地址和WiFi热点等方式获取位置。HTML5中提供了一组Geolocation API(地理位置应用程序接口),用来获取Web用户的地理位置信息,且同样适用于移动设备中。Geolocation API的使用非常简单,在浏览器支持的情况下,使用getCurrentPosition()方法即能获取当前位置的坐标值。

Latest Progress of the Chinese Meteorological Satellite Program and Core Data Processing Technologies

In this paper,the latest progress,major achievements and future plans of Chinese meteorological satellites and the core data processing techniques are discussed.First,the latest three FengYun(FY)meteorological satellites(FY-2H,FY-3D,and FY-4A)and their primary objectives are introduced Second,the core image navigation techniques and accuracies of the FY meteorological satellites are elaborated,including the latest geostationary(FY-2/4)and polar-orbit(FY-3)satellites.Third,the radiometric calibration techniques and accuracies of reflective solar bands,thermal infrared bands,and passive microwave bands for FY meteorological satellites are discussed.It also illustrates the latest progress of real-time calibration with the onboard calibration system and validation with different methods,including the vicarious China radiance calibration site calibration,pseudo invariant calibration site calibration,deep convective clouds calibration,and lunar calibration.Fourth,recent progress of meteorological satellite data assimilation applications and quantitative science produce are summarized at length.The main progress is in meteorological satellite data assimilation by using microwave and hyper-spectral infrared sensors in global and regional numerical weather prediction models.Lastly,the latest progress in radiative transfer,absorption and scattering calculations for satellite remote sensing is summarized,and some important research using a new radiative transfer model are illustrated.

HTML5 Geolocation API研究与应用

web应用与本地应用之争因HTML5的到来变得更加激烈。未来的web应用会大量采用高效和功能丰富的HTML5 API,而地理信息服务作为web应用很重要的一个方面,通过HTML5技术中Geolocation API得到支持和实现。本文研究了Geolocation API的实现机制、隐私模式和使用方法。通过与谷歌地图API结合,设计了一个实际的位置地图应用,展现了Geolocation API的魅力和实用性。相信在未来的应用中,Geolocation API会有更精彩的表现。

Street-Level Landmarks Acquisition Based on SVM Classifiers

High-density street-level reliable landmarks are one of the important foundations for street-level geolocation.However,the existing methods cannot obtain enough street-level landmarks in a short period of time.In this paper,a street-level landmarks acquisition method based on SVM(Support Vector Machine)classifiers is proposed.Firstly,the port detection results of IPs with known services are vectorized,and the vectorization results are used as an input of the SVM training.Then,the kernel function and penalty factor are adjusted for SVM classifiers training,and the optimal SVM classifiers are obtained.After that,the classifier sequence is constructed,and the IPs with unknown service are classified using the sequence.Finally,according to the domain name corresponding to the IP,the relationship between the classified server IP and organization name is established.The experimental results in Guangzhou and Wuhan city in China show that the proposed method can be as a supplement to existing typical methods since the number of obtained street-level landmarks is increased substantially,and the median geolocation error using evaluated landmarks is reduced by about 2 km.

Street-Level IP Geolocation Algorithm Based on Landmarks Clustering

Existing IP geolocation algorithms based on delay similarity often rely on the principle that geographically adjacent IPs have similar delays.However,this principle is often invalid in real Internet environment,which leads to unreliable geolocation results.To improve the accuracy and reliability of locating IP in real Internet,a street-level IP geolocation algorithm based on landmarks clustering is proposed.Firstly,we use the probes to measure the known landmarks to obtain their delay vectors,and cluster landmarks using them.Secondly,the landmarks are clustered again by their latitude and longitude,and the intersection of these two clustering results is taken to form training sets.Thirdly,we train multiple neural networks to get the mapping relationship between delay and location in each training set.Finally,we determine one of the neural networks for the target by the delay similarity and relative hop counts,and then geolocate the target by this network.As it brings together the delay and geographical coordinates clustering,the proposed algorithm largely improves the inconsistency between them and enhances the mapping relationship between them.We evaluate the algorithm by a series of experiments in Hong Kong,Shanghai,Zhengzhou and New York.The experimental results show that the proposed algorithm achieves street-level IP geolocation,and comparing with existing typical streetlevel geolocation algorithms,the proposed algorithm improves the geolocation reliability significantly.

REVERSE-RANGE-DOPPLER METHOD FOR AUTOMATED GEOCODING SAR IMAGES

Range-Doppler (RD) method and Reverse-Range-Doppler (RRD) method are combined together to achieve automatic geocoding of Synthetic Aperture Radar (SAR) image quickly and accurately in the paper. The RD method is firstly used to locate the four corners of the image, then the other pixels of the image can be located by Reverse-Range-Doppler (RRD) method. Resampling is performed at last. The approach has an advantage over previous techniques in that it does not require ground control points and is independent of spacecraft attitude knowledge or control. It can compensate the shift due to the assumed Doppler frequency in SAR image preprocessing. RRD simplifies the process of RD, therefore speeds up the computation. The experimental results show that a SAR image can be automated geocoded in 30 s using the single CPU (3 GHz) with 1 G memory and an accuracy of 10 m is attainable with this method.

Using light-level geolocations to monitor incubation behaviour of a cavity-nesting bird Apus apus pekinensis

The Beijing Swift(Apus apus pekinensis)is a typical cavity-nesting bird that often nests inside holes and crevices in old architectures.Direct observation of their breeding behaviour is challenging and their breeding ecology is thus poorly studied.In this study,we analysed light-level geolocation data collected from six Beijing Swifts for the first time.Our results showed that geolocators can make comprehensive inference of their incubation period and behaviour.As a cost-effective and non-invasive method,geolocators can not only facilitate discovering migration routes,but also can be widely applied in the study of avian reproductive behaviour,especially in cavity-nesting bird species.We further discussed the characteristics and merits of this method and compared with other conventional nest-monitoring methods in recording birds.

解析使用Geolocation API获取地理位置信息

如今社会通信技术和移动互联网技术的发展日新月异,基于地理位置定位的位置服务类Web应用显得越来越重要,作为新Web时代网页设计的技术标准,HTML5提供了Geolocation API接口,能实现地理位置的定位与跟踪。本文解析了如何运用Geolocation API获取用户的地理位置信息并持续跟踪,并将位置信息与Google Map的开放平台相结合,这一功能可以帮助开发者开发基于位置服务的各种应用程序。

HTML 5 Geolocation API应用探究

地理位置(Geolocation)是HTML 5的重要特性之一。地理位置特性提供了确定用户位置的功能,在可允许的情况下,可以把位置分析给别人。识别地理位置的方法有很多,有通过IP地址、利用基站获取手机网络的接入位置、通过利用卫星定位获得经纬度的GPS设备等。对HRML5Geolocation API的应用进行了探究,结果表明,其具有良好的实用性。

Error analysis of stereo SAR geolocation model for spaceborne SAR

Stereo synthetic aperture radar （SAR） geolocation model is an important geolocation model for spaceborne SAR. However, the error of stereo SAR geolocation model has not been analyzed in detail. This paper deduced the geolocation error formulas of the stereo SAR geolocation model and then compared the geolocation error with range Doppler （RD） geolocation model. Through computer simulation, we could get the advantages and disadvantages of the stereo SAR geolocation model.

Factors Associated with Using GPS in Road Accidents at Cotonou in 2019

Introduction: Precise spatial location of accidents is relevant for accidentology researches or road safety investigations. Objective: The aim of this study is to investigate a number of factors associated with the geolocation of road accidents in the city of Cotonou in 2019. Methods: It was a cross-sectional, retrospective study with an analytical focus. Results: This study highlighted a prevalence of coordinates of the GPS reported at 41.63% in 2019 relating to the files of accidents on public roads during the period from April 18 to June 12, 2020. The work was carried out from 384 accident files examined in the 6 districts of Cotonou selected randomly. A logistic regression made it possible to sort out associated factors with using GPS in road accidents. The final model retained through the “ascending step by step” modeling was adopted. The average age of the responsible agents in charge of the observation was around 32 years (32.13 ± 3.17). Geolocation identified associated factors were: the level of instruction with odd Ratio 2 and its 95% confidence interval f [1.02 - 2.40], the means of conveyance odd ratio 2.56 and its 95% confidence interval of [1.21 - 5.41], the severity level of the accident with its odd ratio 4.59 and its 95% confidence interval of [2.82 - 8.32], and the type of day on which the accident occurred with odd ratio 0.56 and its 95% confidence interval f [0.437 - 2.553]. As for the quality of the reported GPS coordinates, 85% of them were good quality. Conclusion: The reduction of road accidents, given its serious nature and extent, requires strategies to promote geolocation of accidents to ensure better identification of risk areas and decision-making adapted to the accident phenomenon.